The technology of athletic and recreational apparel and, notably, footwear has evolved dramatically over the past fifty years. Technical improvements are attributable to use of specially designed polymers, fasteners, liners, soles., etc. often which incorporate physiological/kinesiological performance enhancing features. Typically, such technological improvements first develop in the athletic fields and later migrate into the mass market. The rate of developments has increased, hastened by the continuing growth of commercialism in sports and entertainment. Regardless of the athletic/recreational discipline, virtually every aspect of footwear has been scrutinized to maximize performance and efficiency. For example, not long ago, basketball players wore Chuck Taylors. Today, one would be hard pressed to find a single pair in use. Likewise, in skating, steel blades and leather uppers have been replaced by titanium, composites, and polymers. Correspondingly, it would be imprudent for any athlete not to employ a device that measurably contributes, even if slight, to performance superiority. Although diminishing in substantial enhancement, technological improvements can provide an athlete with an edge, that small increment of enhanced performance permitting peak achievement.
A colorful illustration of athletic footwear development comes from Canada. The Iroquois developed ice skates using animal shinbones tied to footwear with leather thongs. These early skates would allow the user to glide over an icy surface, but without the same degree of confidence that a later evolved leather and steel skate provides. In the past two decades, skates (both ice and roller) have further evolved to incorporate specialize lightweight high strength plastic resins and composites secured to a titanium blade (in the case of ice-hockey skates). That combination produces desirable maximum strength and support while providing optimum weight reduction.
Referring to the constructions of professional level ice skates, typically they are constructed by first molding the boot liner to each of the skater's feet. These very personalized skates are then placed on the feet arid the laces tied. In contrast to the significant improvements in skate construction, the art of lacing skates (or any high performance athletic shoe) has not changed over the centuries. Some lesser level footwear incorporate buckles, VELCRO.RTM., and other lace-substituting securing expedients. However, it is rare at the highest levels of athletics or recreation, that the footwear is not laced. Lacing is an extremely personal activity where an athlete can control the tension and fit of the footwear to maximize performance, a function that can not be replaced by standardized straps and the like. Such standardized attachment devices do not allow an athlete to vary the lace tension along the various zones of the footwear. Not only do the general tension zones vary on the type of footwear, but each athlete has a unique zone tension preference.
Zoning is best defined as employing a specific influence in a given area within the laced area. In sport; professional or recreational, zoning is attempted in several ways. Simply, a lace can be tied with different tensions at certain areas to create zones secured with a knot. FIG. 1 illustrates an example of a zoned lace system on footwear. The upper zone U and lower zone L are tensioned by exerting different forces on the lace in these areas. The knot isolates the upper zone from the free zone F. The free zone is the portion of the lace that is not under tension.
Tensioning a lace in one zone can contribute to enhanced footwear functionality, while exerting a different tension on the same lace in another zone will achieve another specific result. Tension, however, tends toward randomness and migrates from the tighter to the looser. Thus, the differences in tensions between different zones diminish to create a loosening effect in the tighter zone, and conversely a tightening effect in the looser zone. Loosening of footwear is undesirable as it reduces comfort, and support which may lead to a loss of performance. The only solution to regain custom tension is to re-tie the lace or use multiple knots. Constant tying and re-tying of laces due to loosening can be frustrating and time consuming.
Once a lace is tied on a shoe or boot it is important to identify that in fact there are always at least two zones divided by the knot. The zone(s) below the knot, and the not so obvious free zone as shown in diagram 1--the lace above the knot. The tensionless lace in the free zone, above the knot, migrates toward the tensioned lace below the knot which allows the knot to loosen and come undone.
An athlete must employ technique when donning equipment. Indeed, it has been recognized that such technique is as important as the quality and fit of equipment itself. Some athletes prefer extremely tight laces in one zone of their footwear while other zones are only snug. Two players with the same equipment can have completely different strategies to lacing technique. When lacing skates, for example, lacing techniques as it relates to zoning vary not only from discipline to discipline, and skater to skater, but can even vary with the skater from activity to activity.
For instance, two hockey players with the same equipment will tie their skates with their own individual technique accomplishing the common result of ultimate comfort and support. One may increase the tension in the lower zone (lace area between the toes and the top of the instep) and in the upper zone (lace area between the top of the instep and the top of the ankle) by tightening the skate laces as tightly as possible in those zones. Another player, possibly a defensive player, who requires backwards skating and a corresponding range of motion might tie the skate laces as tight as possible in the lower zone and only snug in the upper zone. A figure skater, in contrast, generally leaves the lower zone snug for comfort and circulation. The upper zone, however, is faced as tight as possible for maximum support. Typically, a figure skater will double lace the boot hooks in an effort to retain the tension in the upper zone. While serving to preserve the lace tension, double lacing does not isolate the different zones. The greater exertion of a skater during skating, the more rapidly the tension migrates and the upper zone becomes less taut. It has been reported that 90% of the power delivered to the skate can be lost if the skate is loose.
Other athletic activities in which zoning is involved includes snowboarding (tautness in the upper zone that often requires retying). Runners, both sprinters and long-distance, have great concern with respect to zoning. Some runners employ a method to preserve optimized zoning which involves positively isolating zones. In an effort to overcome the zone-untensioning problem, some runners have developed methods used to retain the selected zone tension. One way to create positively isolated zones is to use more than one lace on the same foot as illustrated in FIG. 2. As illustrated, the main lace is tied conventionally along the length of the upper corresponding to the eyelets E and a second and/or third lace (DL) is tied at the top and bottom of over the upper zone U. Although effective in isolating tension zones, this method requires tying extra knots K, and may result in some modification of the footwear such as cuffing and trimming one end to obtain the correct length. Clearly, a two/multi- lace system is an inefficient solution to the zone tension retention problem.
The composition of the laces themselves, contribute to the degree and rate of zone tension migration. The most effective material for zoning is a cotton lace due to the friction between the lace and the eyelet helping to retain tension in the zones. However, cotton, being biodegradable, does not respond favorably to moisture. Polyester lacing, although having moisture resistant capacity and being capable of being tied with more tension than cotton does not frictionally engage with the shoe eyelet as well as cotton. This is due to the fact that polyester causes less friction at the eyelet compared to cotton. Polyester laces are smooth and slide easily through eyelets. Therefore, although the lace is tighter, the lace is not able to retain zone tensioning. Migration of tension occurs rapidly with polyester laces.
One technique has been reported to combine the advantages of both lace types. Athletes can apply wax to cotton laces which, during lacing, allow the lace to slide with less friction through the eyelet. Friction between the lace and the eyelet causes the wax to melt reducing friction at the eyelet. Once laced, the wax at the eyelet cools and becomes sticky. This stickiness slows tension migration between zones.
The foregoing underscores the problems associated with conventional shoe/boot laces and methods, particularly in high performance athletic endeavors Furthermore, the foregoing highlights a need for a tension zone adjunct for lace footwear to reduce the need for lacing technique compromises.